The HALT-Polycystic Kidney Disease (PKD) trials comprise 2 fully enrolled randomized controlled trials (A & B) conducted at 7 clinical sites supported by a central imaging facility, a drug distribution center, and 2 central laboratories. HALT-PKD Study A uses a 2x2 factorial design to evaluate the impact of rennin-angiotensin-aldosterone system (RAAS) blockade and 2 levels of blood pressure control on structural progression of disease in 558 high-normal or hypertensive PKD patients with estimated glomerular filtration rate (GFR) >60 ml/min/1.73m2. The primary outcome is total kidney volume (TKV) measured at 0, 24, and 48 months. HALT- PKD Study B evaluates the impact of RAAS blockade on progression of disease in 486 hypertensive PKD patients with estimated GFR 30-60 ml/min/1.73m2. The primary outcome is a combined endpoint defined by >50 percent reduction in eGFR, ESRD, or death. Participants are followed for 4-7 years. For Study A, there is strong evidence to show the impact of TKV on kidney function (GFR) takes several years to manifest implying the short period of follow-up for Study A (48 months) may be insufficient to see changes on kidney function. For Study B, the observed number of endpoints at 5 years is lower than had been predicted to provide power for 25 percent reduction in outcome. As a result of these new findings and interim analyses, the DSMB approved extension of both studies through July 2014 to allow an additional measure for Study A (60 months) and 5-8 years follow-up for study B. We propose to continue to serve as the HALT-PKD DCC by 1) collaborating with study investigators, managing protocol and regulatory compliance, facilitating the transfer of data, images, and bio-specimens, and supporting HALT- PKD activities for quality control, endpoint adjudication, and blood pressure management; 2) maintaining the Web-based data management system that incorporates data tracking, entry, quality control, and report generation; 3) conducting interim and final statistical analyses to support the study aims including the future primary analyses for Study A and Study B. Public